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I have noticed in the last couple of weeks, when I put my roof down, it seems to have developed quite a loud "thunk" to it, i was wondering if its just the hot weather making the hydraulic fluid thinner, therefore less resistance, or is it something else?

Which part of the process is the 'thunk' ?

Do you mean it flops shut over the last few inches of the close operation? Mine has always done that a bit. I usually put my left hand up to ease the weight over those last couple off inches of travel.

geordie_zed wrote: ↑Wed Jul 11, 2018 5:16 pm Which part of the process is the 'thunk' ?

Sorry should have given more info, its the last bit when the roof is closing, when the rear window comes down and shuts

RustyZ4 wrote: ↑Wed Jul 11, 2018 5:38 pm

geordie_zed wrote: ↑Wed Jul 11, 2018 5:16 pm Which part of the process is the 'thunk' ?

Sorry should have given more info, its the last bit when the roof is closing, when the rear window comes down and shuts

Ah just spotted it's an E89 thread

Mine as always done that, for the five years i have owned it. My roof is opened everyday, during summer months.

Mine also does the same seems to be fairly normal

Mine, too.

Higher temps would make the hydraulic fluid less viscous, which could give a less “damped” operation.
Wait till the temperature drops & see if it becomes less slammy
Rob

Busterboo wrote: ↑Wed Jul 11, 2018 10:32 pm Mine, too.

It’s that 98ron petrol you’ve put in it doing that

98 RON? Me? Nah. Never have, never will.

If the cylinders are designed properly they would have a last moment slow down port built into the piston to cushion the end of travel.
I think at the point of closing there is simply too much weight at that leverage for the cylinder to cushion the blow.
https://www.cylinder.co.uk/technical/hy ... types.html

Mine won't open currently (need to get it booked in when I get a chance) so complete lack of thunks and my neighbor thought it was a Coupe until I explained my roof mechanism is stuffed

Thanks all, everything works ok (that will be the kiss of death ) maybe I am just noticing it more these days

Mine gives a good thunk! Hadn't really noticed it before but now I'm hearing it a few times a day...